The county I live in (Multnomah) in Oregon banned plastic bags so most people use reusable bags or the store's (compostable) paper bags. Many of our neighboring counties still allow plastic bags though, so the impact has been negligible.
For a brief time stores handed out 3 reusable bags to every customer that had one of their loyalty cards. Now you have to buy them for $1.00.
If you want to look at an area that has a variety of laws regarding shopping bags look at Portland, Oregon. Three counties comprise the metropolitan area (Washington, Multnomah, Clackamas) and the laws vary from county to county. In fact, you can cross the street in some areas and encounter different laws.